Combine two MySQL fields and update a third one with result?

Following is the syntax to combine two fields in MySQL −

alter table yourTableName add column yourColumnName dataType;
 update yourTableName set yourAddedColumnName =concat(yourColumnName1,' ',yourColumnName2);

Let us first create a table −

mysql> create table DemoTable1590
   -> (
   -> FirstName varchar(20),
   -> LastName varchar(20)
   -> );
Query OK, 0 rows affected (0.57 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1590 values('Adam','Smith');
Query OK, 1 row affected (0.45 sec)
mysql> insert into DemoTable1590 values('John','Doe');
Query OK, 1 row affected (0.42 sec)
mysql> insert into DemoTable1590 values('David','Miller');
Query OK, 1 row affected (0.16 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1590;

This will produce the following output −

+-----------+----------+
| FirstName | LastName |
+-----------+----------+
| Adam      |    Smith |
| John      |      Doe |
| David     |   Miller |
+-----------+----------+
3 rows in set (0.00 sec)

Following is the query to combine two MySQL fields and update third field after concatenation −

mysql> alter table DemoTable1590 add column FullName varchar(40);
Query OK, 0 rows affected (0.54 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> update DemoTable1590 set FullName=concat(FirstName,' ',LastName);
Query OK, 3 rows affected (0.56 sec)
Rows matched: 3  Changed: 3 Warnings: 0

Let us check the table records once again −

mysql> select * from DemoTable1590;

This will produce the following output −

+-----------+----------+--------------+
| FirstName | LastName | FullName     |
+-----------+----------+--------------+
| Adam      |    Smith | Adam Smith   |
| John      |      Doe | John Doe     |
| David     |   Miller | David Miller |
+-----------+----------+--------------+
3 rows in set (0.00 sec)